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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Chemical Recycling of Poly(ethylene terephthalate): Effects of Mechanical Stress and Radiation Damage on Hydrolysis

Zhang, Tongjie 10 May 2020 (has links)
Finding an effective recycling process for oceanic plastic waste is increasingly important to address environmental pollution. Plastic waste is a bountiful and sustainable resource for energy production and chemical recycling. Polyethylene terephthalate (PET), one of the most common commercialized polymers, is promising to be recycled by hydrolysis. The objective of this work was to study the effects of mechanical stress and radiation damage on PET structure and hydrolysis reactivity. Ball-milling and photo-damaging pretreatments were carried out to imitate the environmental degradation in the ocean environment. An evident decrease in crystallinity with increasing ball-milling time was observed. This decrease in crystallinity caused by fractures of chemical bonds induced by photoaging and ball-milling treatments were investigated. PET was hydrolyzed into ethylene glycol (EG) and terephthalic acid (TPA) at 200°C in tube hydrolysis reactors without catalysts. EG and TPA were recovered after PET depolymerization. Thermogravimetric analysis and Fourier-transform infrared spectroscopy indicated that the recovered TPA was purified. Qualitative and quantitative analysis of TPA and EG were performed by using UV-Visible spectrophotometer and High-Performance Liquid Chromatograph (HPLC) separately. At 200 ℃, the conversion rate of fresh and ball-milled PET samples was improved from 16-18% with a one-hour reaction time compared to 87-91% with a two-hour reaction time. This depolymerization behavior supported that the conversion rate of PET was increased with increasing reaction time at the same temperature. The experiment results, however, showed PET conversion, TPA yield, and EG yield did not improve after ball-milling and photo-damaging treatment. After retention time of 1 hour, PET conversions, yields of TPA, yields of EG of various PET samples were 16.5±1.5%, 11.5±1.5% and 0.70 ± 0.20%, respectively. Mechanical treatment and radiation damage did not affect PET reactivity significantly in this experiment. Two main reasons were discussed to explain this result. The effect of radiation damage and mechanical stress was obscured by the more dominant reaction condition, temperature. The pretreatments in this experiment were not strong enough to affect PET reactivity. Based on the current results, recommendations for the hydrolysis temperature, potential catalysts, and more robust pretreatment methods were provided for further outlook of studying environmental effects on PET hydrolysis.

Depolymerisation of poly(ethylene terephthalate) for recycling

Phillips, Julia January 1994 (has links)
No description available.

Molten Salt Pyrolysis of Polystyrene: Optimization and Investigation of Reaction

Yang, Zhengyang 24 April 2017 (has links)
Waste plastic treatment was a global issue currently. A sustainable recycling process was required to recovery the monomer units from the polymer, thus avoiding environmental impacts due to disposal and enhancing the economic benefit from the recovered products. Pyrolysis was one of the promising process and previous MQP group has studied the pyrolysis with molten salts. In this work, a standardized and optimized pyrolysis reaction process of polystyrene was developed, based on the previous work on molten salt pyrolysis 5. The literature of pyrolysis mechanism and catalytic effects were reviewed as a guide process design. The orientation of the reactor was standardized to be consistent with literature record of preceding work. The positioning of the flow tube for the carrier gas and thermocouple were standardized in locations to provide mixing process of the reactant, the removal of products, and the accurate measurement of reaction temperature. The product collection system was also investigated and optimized to maximize collection efficiency while avoiding excessively low temperatures. The experiment results with standardized reaction configuration showed an improved styrene yield, 65%, compared with a previous yield of 44%. Then with the standardized reaction configuration, the catalytic effects of molten salt were studied at 400℃ pyrolysis temperature. Quantitative analysis indicated that the molten salt improved the styrene selectivity of the monomer compared to the dimer. Analysis of product composition and mass balance indicated formation of heavy non-GC detectable species in the liquid products. Gas phase secondary reaction during pyrolysis, and re-polymerization inside the liquid products, were discussed to explain the different styrene yield and the existence of heavy species. Based on the current results, recommendations for the pyrolysis temperature, initial reactants loading, and condenser temperature and analysis strategies were provided for further study of the molten salt pyrolysis of polystyrene.

New compatibilizing agents for blends of linear low-density polyethylene and polystyrene as model systems of the post-consumer plastic waste stream

Li, Tao January 1994 (has links)
No description available.

Technologické koncepty pro čištění oceánů / The ocean cleaning technology concepts

Jedličková, Kateřina January 2020 (has links)
The main aim of this master's thesis is the world ocean pollution by plastic waste. The introductory part of the thesis contains general information about the production of plastics and plastic waste, followed by data on ocean pollution by plastic waste including the estimated amount, pollution sources, and composition. Part of the thesis consists of the introduction of known concepts that are already actively looking for a solution to marine waste and of their mutual comparison. The following part deals with the plastic waste management, the possibilities of its treatment and utilization. The last area is the draft of an alternative system that is focused on an effective solution in accordance with environmental aspects. Within this draft, a material and economic balance is made.

The Management of CSR within the plastic industry : A study of plastic producing companies within the Gnosjö region in Sweden / Ledningen av CSR inom plastindustrin : En studie av plastproducerande företag inom Gnosjöregionen i Sverige

Avramidou, Sara, Tellstedt, Maria January 2020 (has links)
Background: The matter of Corporate Social Responsibility (CSR) has more and more become a topic of interest today. As the concept has gained attention, the emphasis on its different concepts has shifted from the focus lying on the social responsibilities, to being more about the environmental responsibilities and impact of companies. Although the attention put on CSR and the environment has increased, an increase in the amount of plastic waste is still seen in the world. In Sweden, corporations accounts for as much as 50% of the total amount of plastic waste every year.   Purpose: The purpose of this thesis is to analyse the management of environmental Corporate Social Responsibility in plastic producing companies, specifically the management of CSR within the Gnosjö region in Sweden   Method: This qualitative study involves multiple case studies primarily based on semi-structured interviews with managers of plastic producing companies in the Gnosjö region of Sweden.   Findings: The study showed that plastic companies are challenged in several ways, like re-using their production waste, caring for their employees, switching to more sustainable energy sources, and adhering to sustainable standards. Thus, companies’ goals are required to satisfy environmental demands by positioning their CSR-work towards customers’ environmental needs.   Conclusion: This thesis conclude that companies’ have different views on the meaning of CSR. It was found that sales and profit were the main motivators of adopting CSR practices, followed by some ethical aspects. Companies will continue to experience an increased demand for recycled plastics and that the importance of CSR will persistently grow. New knowledge demands the development of new materials and better strategies for recycling.

Výroba drtiče na plastový odpad / Production of crusher on the plastic waste

Květoun, Jan January 2019 (has links)
This thesis is focused on designing and manufacturing a shredder for plastic waste 2H for small companies, households and blocks of flats. Thesis contains brief description of plastics, their properties and usage in praxis. It deals with excessive production of plastic, noncircular economy of waste and unsatisfactory processing of plastic waste. There are examples of collecting, sorting and recycling technologies and their application in praxis. It consists of current overview of shredders available on Czech and Slovak market and their comparison. Practical part of this thesis focuses on design itself, its components, parameters and economic issues of manufacturing. Annex contains 3D model of shredder assembly, bought components overview, assembly drawings and photo documentation of created shredder.

From Waste To Worth: How To Optimize Industrial Plastic Waste Management? : A Case Study Of A Small To Medium-Sized Company

Talaat Abdelaziz Mosutafa, Heba January 2023 (has links)
Plastic waste from industries and manufacturing development poses a significant issue due to its exponential environmental and economic impacts. This study aims to optimize the industrial plastic waste management by exploring the different ways of handling this waste for small to medium-sized enterprises (SMEs) in the energy production sector in line with the EU and Swedish waste directives. This study draws on a mixed research method and a case study. The results disclose that proper sorting system, the implementation of waste policies and regulations, and informed waste practices based on knowledge and education in plastic waste management are essential for the implementation of sustainable plastic waste management system. While aspects such as the market demand and economic efficiency, the presence of hazardous and waste contamination, and the waste volume were identified to hinder the implementation. However, this study explored sorting techniques through the lens of practical strategies, introducing innovative solutions to address the challenges associated with mixed and contaminated industrial plastic waste. By leveraging the selective dissolution sorting technique, the study proposed the waste sorting process as essential practices to pave the way for sustainable waste management practices in SMEs in the energy sector. The findings not only contribute to the existing knowledge in waste management but also offer practical recommendations for businesses striving for efficient waste management. However, these findings necessitate implementing new protocols for waste sorting and changes in waste flow to ensure effective sorting practices. This could require investments in equipment, training for employees, creating specialized waste management department or establishing cross-functional teams to oversee waste sorting initiatives.

Co-pelletization of corn stover and plastic waste as an alternative fuel

Stockham, Haley January 2021 (has links)
No description available.

Эколого-экономическая эффективность переработки бытовых пластиковых отходов : магистерская диссертация / Environmental and economic efficiency of household plastic waste recycling

Паситов, В. И., Pasitov, V. I. January 2019 (has links)
Пластиковые отходы занимают первое место по стоимости и скорости накопления среди твердых коммунальных отходов. Вторичное использование отходов пластика способствует существенному сокращению использования первичных ресурсов, снижению вредного воздействия на окружающую среду. Цель исследования заключается в разработке практических рекомендаций по оптимизации схем переработки бытовых пластиковых отходов на основе оценки их эколого-экономической эффективности исходя из анализа существующей ситуации в системе обращения с отходами в Свердловской области. В работе проведен анализ региональной политики по обращению с отходами и опыта переработки твердых коммунальных отходов. Предложен проект по созданию производства по переработке ПЭТ-пластика с оценкой его эколого-экономической эффективности. Впервые количественно оценен дополнительный экологический эффект от замены первичного сырья на вторичное при реализации проекта. / Plastic waste takes first place in terms of cost and rate of accumulation among municipal solid waste. Recycling of plastic waste contributes to a significant reduction in the use of primary resources, reducing the harmful effects on the environment. The purpose of the study is to develop practical recommendations for optimizing recycling schemes for household plastic waste based on an assessment of their environmental and economic efficiency based on an analysis of the current situation in the waste management system in the Sverdlovsk region. The work analyzes the regional policy on waste management and the experience of processing municipal solid waste. A project is proposed to create a production for processing PET plastic with an assessment of its environmental and economic efficiency. For the first time, the additional environmental effect of replacing primary raw materials with secondary ones during project implementation was presented.

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